1. Field of the Invention
The present invention relates to a method and equipment for dividing slabs into predetermined widths.
2. Description of the Prior Art
There have in the late years been many cases in which a slab produced by continuous casing equipment or blooming mill is split lengthwise into sections of predetermined width. When to obtain small-width slabs, for instance, if they are each made as predetermined in continuous casting equipment or a small ingot casting mold, their productivity is low and that uneconomical.
For such reasons, it is customary in the prior art to manufacture, by continuous casting equipment or a large ingot casting mold, a slab having a width of an integral multiple of predetermined dimension and then divide, by means of gas cutting, the slab lengthwise into at least two, obtaining slabs of the desired width.
Nevertheless, such dividing work, instead of being made on the slab conveying table, is carried out after shifting the slab elsewhere; so its shift is very troublesome.
For instance, the slab having a width of an integral multiple of the present dimension, manufactured by continuous casting or large ingot casting equipment (hereinafter referred to simply as continuous casting equipment), is shifted by the conveying table for specified treatment but, in this case, the slab has to be removed by a lifting magnet crane or the like from the conveyance table to somewhere else, for example, to an earth floor where to divide the slab lengthwise by means of gas cutting. After the dividing operation, the individual slabs each have again to be moved by a crane or the like from the earth floor to the conveyance table or somewhere else for the next treatment. Consequently, such slab shifting operations involve much troublesomeness, affecting the productivity of slab manufacture. To avoid this, a slab dividing device has been proposed which divides the slab of an integral-multiple width by gas cutting on the conveyance table. Even such a proposed device is attended with the possible danger of cutting rollers of the conveyance table when the slab is divided by gas cutting in the state of being carried by the table. Accordingly, the slab to be cut is conveyed by the conveyance table, whereas the torch of the cutting device used is held as fixed in respect of the conveyance table and it is constituted not to interfere with the conveyance rollers.
With the slab dividing device of such an arrangement, however, since the slab is cut while being moved relative to the fixed cutting torch, it is necessary to carry out centering of the slab precisely but this centering is extremely difficult. That is to say, the centering of the slab is performed by moving it along a guide. In this case, the slab movement must be constituted not to stop by being interfered with by the guide.
However, there exist unevennesses on the side surfaces of the slab, which are invisible to the naked eye, so they are liable to catch the gide, causing the slab to stop. To eliminate such catches, the guide has to be constituted as a large-scale device. And, as the guide is so designed as to be detachable after the centering operation, errors can occur in the center of the slab during its movement, owing to warping of the slab in its lengthwise direction, which obstruct high-precision dividing of the slab.
In addition, since along the underside edges of the cut surface of each slab there are deposited slags, if the slab is rolled in that state, the slags cut deeply into the slab, remaining therein as permanent impurities. It is therefore necessary to eliminate such slags before rolling. Nevertheless, in actuality, the elimination of such slags is now carried out manually after turning over the slab following the dividing operation.